This invention relates to ultrasonic scanning apparatus.
The diagnosis of living organs, such as the examination of the breasts for cancer, can be accomplished by passing ultrasonic waves through the organ, either in transmission or by reflection. The scanning of the entire area of the organ can be accomplished by moving the transducers in a raster to cover all regions thereof. Inasmuch as subtle changes in tissue density must be detected, it is important that there be uniform transmission paths between the transducers and the organ at all positions of the scanning transducers, so that only the non-uniformities in the tissue cause changes in the detected signal.
One method which can be used to scan a breast or other organ, involves the immersion of the organ and of the transducers in a common pool of water. The water transmits the ultrasonic waves with minimal loss and distortion. A system utilizing such immersion techniques is described in U.S. Patent Application Ser. No. 679,732, filed Apr. 23, 1976. Such direct immersion has several disadvantages. Where the breast of a patient is to be scanned by placing the patient prone over a water tank with the breast immersed, it is difficult to immerse the base or pectoral portion of the breast while keeping the head of the patient out of the water. Also, the breast is unrestrained and therefore the image can be blurred if there is any movement. Furthermore, the need to have the patient lie prone and immersed in water is somwhat uncomfortable and precautions must be taken to prevent contamination of the water.